CASE OF THE MONTH

Pulmonary Alveolar Proteinosis

The patient is a 60 year old female who presents with a six month history of nonproductive cough. She was treated empirically with antibiotics without improvement. On admission, she is hypoxic and requires oxygen. The patient has never smoked, has had no recent travel, and denies exposure to chemicals/irritants. She does have history of breast cancer treated with radiation and chemotherapy.

CT scan of the lung shows nonspecific bilateral infiltrates and no discrete legion. Wedge biopsies of the left lung were performed, and the surgeon noted abundant milky white fluid associated with lung tissue.

Microscopically, the alveolar spaces are filled with dense granular eosinophilic material with scattered larger inclusions, which are more intensely eosinophilic. A PAS special stain is positive in the intra alveolar material. No significant inflammation, granulomas, or fibrosis is seen.

The findings are characteristic of pulmonary alveolar proteinosis (PAP).

PAP is a rare disease with an incidence of less than 1 case per million people. The reported causes of PAP, apart from idiopathic, include dust related occupations, drug effect, hematologic malignancy, and immunodeficiency.